Higher Survival Capacity Research Articles

Leaf drought adaptive response in winter oilseed rape is altered at the onset of senescence: a study combining NMR relaxometry, multi-omics and microscopy.

Climate change is bringing more frequent and intense droughts, reducing overall water availability and adversely affecting crops. There is a need to improve our understanding of the tissular and cellular adaptation mechanisms that are critical for plant water conservation strategies. Here, we have used NMR relaxometry in combination with microscopy and multi-omic analysis to study the effects of progressive soil drought on winter oilseed rape (WOSR, Brassica napus L., cv. Aviso) leaves. This study reveals the structural and metabolic adjustments these leaves operate to maintain cell homeostasis. Our results are original in showing that the adaptive responses are altered in leaves at the onset of senescence, associated with changes in metabolic plasticity and mesophyll structures. Thus, long-term responses in young leaves involving osmotic adjustment were combined with the maintenance of tissue hydration and cell growth, contributing to high survival and recovery capacity. For the first time, short-term responses observed in early senescent-old leaves were associated with early drought-induced dehydration of the spongy layer. However, this dehydration was not followed by osmotic adjustment and did not allow maintenance of leaf tissue turgor. These findings open further studies on the genetic variability of drought responses related to identified short- and long-term structural and metabolic plasticity traits in Brassica species.

Relationship between germination under osmotic stress and development in Bouteloua curtipendula genotypes: implications for restoration management

Several studies have used chemical agents to inhibit the osmotic potentials and simulate water stress conditions in vitro, assuming that tolerance to osmotic stress is an advantage for seedling survival and establishment in the field. However, how the germination and seedling growth in the laboratory contribute to seedling emergence, survival and establishment are not well-known. We evaluate the relationship between the resistance to the in vitro osmotic stress and the emergence, establishment, and survival under field conditions in sideoats grama (Bouteloua curtipendula). The resistance to osmotic stress was evaluated in the osmotic potentials 0, −0.5, −1.0, and −1.5 MPa, simulated in the laboratory. The emergence, establishment, and survival under field conditions were evaluated in two experimental sites for two years. Results from this study revealed that the survival in the field was positively related (p < 0.05) to the inhibition of germination (R 2 = 0.68), germination speed index (R 2 = 0.69), and plumule length (R 2 = 0.68) determined in the laboratory. In other words, the genotypes most affected by the in vitro osmotic stress presented the greatest survival and establishment in the field. This information should be considered for selecting new sideoats grama genotypes of high survival and establishment capacity in natural conditions.

Thermal tolerance of Acartia tonsa: In relation to acclimation temperature and life stage.

The Acartia tonsa, a calanoid copepod species, has high survival and thermal acclimation capacity in aquatic environments characterized by temperature variations. Dynamic and static thermal polygon areas of this species are 495 °C2 and 267 °C2 for nauplii stage, while adult stage has 747 °C2 and 411 °C2 dynamic and static thermal polygon area, respectively. In addition, Acartia tonsa is a copepod species which is more resistant to both high and low lethal temperatures, with its resistance zone of 105 °C2 and 131 °C2 for nauplii and adults, respectively. Acartia tonsa nauplii acclimated to 18°C, 23°C and 28°C have lover and upper thermal limit (CTMin-CTMax) of 6.82-26.15°C, 8.65-29.49°C, and 11.70-34.10°C, respectively. This species in the adult stage has a CTMin-CTMax of 4.47-30.30°C, 6.35-33.94°C, and 9.92-35.90°C at acclimation temperatures mentioned above. Its broad dynamic and static thermal tolerance polygon areas and, accordingly, its significant thermal limits allow Acartia tonsa to survive at warm or cold extremes in their natural environment.

RGS2-mediated translational control mediates cancer cell dormancy and tumor relapse.

Slow-cycling/dormant cancer cells (SCCs) have pivotal roles in driving cancer relapse and drug resistance. A mechanistic explanation for cancer cell dormancy and therapeutic strategies targeting SCCs are necessary to improve patient prognosis, but are limited because of technical challenges to obtaining SCCs. Here, by applying proliferation-sensitive dyes and chemotherapeutics to non-small cell lung cancer (NSCLC) cell lines and patient-derived xenografts, we identified a distinct SCC subpopulation that resembled SCCs in patient tumors. These SCCs displayed major dormancy-like phenotypes and high survival capacity under hostile microenvironments through transcriptional upregulation of regulator of G protein signaling 2 (RGS2). Database analysis revealed RGS2 as a biomarker of retarded proliferation and poor prognosis in NSCLC. We showed that RGS2 caused prolonged translational arrest in SCCs through persistent eukaryotic initiation factor 2 (eIF2α) phosphorylation via proteasome-mediated degradation of activating transcription factor 4 (ATF4). Translational activation through RGS2 antagonism or the use of phosphodiesterase 5 inhibitors, including sildenafil (Viagra), promoted ER stress-induced apoptosis in SCCs in vitro and in vivo under stressed conditions, such as those induced by chemotherapy. Our results suggest that a low-dose chemotherapy and translation-instigating pharmacological intervention in combination is an effective strategy to prevent tumor progression in NSCLC patients after rigorous chemotherapy.

Identification of stress tolerant rhizobial strains inhabiting &lt;em&gt;Gliricidia sepium&lt;/em&gt; in Polonnaruwa district, Sri Lanka

Rhizobia are well-reputed biological nitrogen fixing organisms due to their proficiency in symbiotic root nodule formation with leguminous plants. Gliricidia sepium is a widely distributed legume which hosts a wide range of rhizobia. Few studies have been carried out to identify the stress tolerant rhizobial populations inhabiting G. sepium in Sri Lanka. This study was focused on the characterization and identification of stress tolerant rhizobial strains residing in the root nodules of G. sepium growing in seven selected locations of Polonnaruwa district, Sri Lanka. Isolated rhizobial strains were separately subjected to stress conditions (pH, temperature, salinity, and drought) and to a combination of given stress conditions. Most of the strains were tolerant to 25 - 45oC temperature range, extreme drought conditions and 1.5 % and 2.0 % salinity levels. However all the strains were adversely affected by acidic pH. Among the fifteen strains that were selected from the statistical analysis, fourteen displayed higher survival capacity when the combinations of physiological conditions were applied. There was great genetic diversity within these isolates and they belonged to 10 clusters. Cross inoculation of these isolated stress tolerant strains into crop legumes can be used as an ideal alternative for chemical nitrogen fertilizers.

A STUDY OF POTENTIAL LISTERIOSIS: AN EMERGING FOOD-BORNE DISEASE

The incidence of listeriosis has been rising 1980s. Epidemic outbreaks are becoming more widespread and are accompanied by high mortality. The most common cause of infectionis consumption of food contaminated with pathogenic Listeria species, in particular L. monocytogenes . Listeria bacteria are psychrophiles, live in all media of the environment, and easily move from saprotrophic to parasitic mode of life. All these qualities have provided them with adaptability and high survival capacity. The sources of food contamination with Listeria bacteria usually are contaminated raw materials or equipment of food production facilities. Deep frozen beef blocks were tested for contamination with Listeria bacteria that were detected and identified by bacteriological technique and enzyme immunoassayand immunochromatographic assay. Listeria bacteria were found in 35% of samples but there were no pathogenic species among them. The isolated species were identified as L. innocua, L. welshimeri, L. grayi and L. seeligeri . These species often colonisevarious media of the environment. The examined meat samples were found to be safe. Listeriosis can be prevented by systemic proactive measures including sanitary and epidemiological control of food raw materials and finished products, properly organized technological process, and hygienic education of the population.

Identification of Soybean Genotypes Resistant to Charcoal Rot by Seed Inoculation With Macrophomina phaseolina

Soybean charcoal rot is a widespread root disease caused by the fungus Macrophomina phaseolina, a natural soil inhabitant that has great pathogenic variability and high survival capacity under adverse conditions. There are no registered fungicides or genotypes genetically resistant to this disease, although differences in susceptibility have been observed. As the fungus is a seed-borne pathogen, screening methods based on seed inoculation are quick and efficient. The objective of this work was to assess the efficiency of soybean seed infestation by incubation for 48 h with colonies of M. phaseolina, comparing two germination environment methods (germination paper or in pots with substrate), and to correlate the relative germination of genotypes of both methods with the severity of charcoal rot observed in a field test. The results showed that 48 h were sufficient to infest seeds and reduce the germination. The germination in paper was higher at 5 days after sowing (DAS) than that in pots at 8 DAS in a greenhouse. Both environments exhibited a highly negative correlation between seed germination and field disease severity (r = -0.775 in germination paper and r = -0.779 in pots with substrate). It is recommended that the germination test be performed in germination paper due to practicality and economy of space, material, and labor besides the better control of the environment.

Isolation and characterization of a virulence related Vibrio alginolyticus strain Wz11 pathogenic to cuttlefish, Sepia pharaonis

Vibrio alginolyticus is a ubiquitous marine opportunistic pathogen that can infect various hosts in marine environment. In the present study, V. alginolyticus strain Wz11 was isolated from diseased cuttlefish, Sepia pharaonis, with 20% of promoted death and high survival capacity in skin mucus and tissue liquid. Its growth, siderophore production, and expressions of haemolysin and swarming related genes were characterized under iron limited conditions. The minimal inhibitory concentration (MIC) of 2,2′-dipyridyl (DP) to V. alginolyticus strain Wz11 was 640 μM. While growth of V. alginolyticus strain Wz11 was inhibited by DP, production of iron-seizing substances, haemolytic activity and swarming motility were increased. Moreover, expressions of haemolysin related genes tlh, tdh and vah and flagellar related genes flgH, fliC, fliD and fliS were also characterized using real-time reverse transcriptase PCR. Expression of tdh was up-regulated to 7.7-fold, while expressions of tlh and vah were down-regulated to 0.016-fold and 0.03-fold, respectively. The expression of fliC, flgH, fliD and fliS was up-regulated to 4.9-, 3.8-, 8.6- and 4.5-fold, respectively. Concluded from our results suggested that V. alginolyticus strain Wz11 was considered as a potential pathogen of S. pharaonis, and iron level played an important role in the production of iron-seizing substances, and activities of haemolysin and bacterial swarming as well as their related gene expressions.

Immune response induced by fermented milk with potential probiotic strains isolated from artisanal Cocido cheese

ABSTRACT Fifteen strains of lactic acid bacteria isolated from artisanal Cocido Mexican cheese were evaluated for their probiotic potential and capacity to modulate the immune system. The results revealed that the strains J20, J23, J24, J25, J27, J28, J32 and J37 presented the highest potential probiotic. Some strains showed resistance to antibiotics; however, they did not exhibit haemolytic activity or mucin degradation. The auto-aggregation capacity ranged from 9.54% to 47.80%, and the hydrophobicity was 21.1%, 63.4% and 78.8% for J27, J24 and J37, respectively. The strains showed high survival capacity (>80%) under different storage conditions and the β-galactosidase activity was 241.77–249.25 MU. Furthermore, the administration of fermented milk by specific strains of Lactobacillus enhanced IL-10 levels and upregulated IL-6 and IgA levels in serum samples of rats. Therefore, the evaluated strains may modulate the immune system and may be good candidates for their inclusion in the manufacture of probiotic-fermented milk.

L-Arginine Modulates T Cell Metabolism and Enhances Survival and Anti-tumor Activity

SummaryMetabolic activity is intimately linked to T cell fate and function. Using high-resolution mass spectrometry, we generated dynamic metabolome and proteome profiles of human primary naive T cells following activation. We discovered critical changes in the arginine metabolism that led to a drop in intracellular L-arginine concentration. Elevating L-arginine levels induced global metabolic changes including a shift from glycolysis to oxidative phosphorylation in activated T cells and promoted the generation of central memory-like cells endowed with higher survival capacity and, in a mouse model, anti-tumor activity. Proteome-wide probing of structural alterations, validated by the analysis of knockout T cell clones, identified three transcriptional regulators (BAZ1B, PSIP1, and TSN) that sensed L-arginine levels and promoted T cell survival. Thus, intracellular L-arginine concentrations directly impact the metabolic fitness and survival capacity of T cells that are crucial for anti-tumor responses.

Consequences of morphological plasticity and fragmentation on space occupation of coral reef macroalgae

The macroalgal species, Halimeda tuna, Halimeda opuntia, and Dictyota sp., are modular and clonal organisms that have the capability for morphological plasticity and asexual reproduction through fragmentation. Growth and disturbance factors affect these characteristics and consequently their rate and amount of space capture. A three-dimensional agent-based model SPREAD (Spatially-explicit Reef Algae Dynamics) was used to explore these potential consequences under a range of growth and disturbance conditions, and to investigate the particular conditions leading to variations of these macroalgae in the inshore patch and offshore reefs in the Florida Reef Tract. The morphology of macroalgae, particularly for H. tuna, had an effect on the rate and amount of space occupation, where larger and more upright forms were able to attain greater cover. Even with the more prolific growth forms, space occupation was still limited. Inclusion of fragmentation was needed for greater expansion and to obtain abundances comparable to field observations. Disturbance, whether through herbivory or stronger forces like storms, interacts with fragmentation in determining space occupation patterns of the macroalgae species. High disturbance levels can promote increased fragmentation and spatial cover. However, this appears to be only true for H. opuntia and Dictyota sp., species with relatively high fragment survival capacity. H. tuna achieved higher cover at low disturbances. Strong disturbances leading to larger fragment sizes were detrimental to the spatial spread for all species. Temporally, these macroalgal populations in the studied reefs appeared to be stable overall with seasonal increases and decreases, as was shown possible in the model, observed in the field, and supported in the literature. Based on SPREAD and corroborated with field observations, the combined inherent growth requirements, capability for fragment success, and disturbance through fragment generation influenced the abundance of these macroalgae in inshore patch and offshore reefs which experienced different growth and disturbance conditions. The overall stable macroalgal cover in the observed and simulated Florida Keys reefs permits other organisms, particularly hard corals, to capture space on the reef. Nonetheless, specific local conditions and the timing of macroalgae seasonal increases can impact the spatial spread of other benthic organisms.

Growth and reproductive post-fire responses of two shrubs in semiarid Patagonian grasslands

Variation in fire intensity affects the post-fire survival and growth of shrubs. We examined effects of maximum fire temperature (a proxy for fire intensity) on the survival, growth and reproductive performance of the shrubs Mulinum spinosum and Senecio bracteolatus at 1 and 2 years post-fire in north-west Patagonian grasslands. We applied two fire temperature treatments to plants of each species. All M. spinosum plants survived fire treatments but high fire temperature notably decreased survival of S. bracteolatus. Bud position and plant architecture probably influenced shrub survival. During the first growing season, M. spinosum did not produce seeds whereas S. bracteolatus plants burned at low temperature produced three times more seeds and bigger seeds than unburned plants. Also, seeds from burned plants of S. bracteolatus had higher germinability than seed from unburned plants. High survival and resprouting capacity of M. spinosum even after high fire intensity indicate that this species might be less affected by changes in fire regime.

IL-7 promotes long-term in vitro survival of unique long-lived memory subset generated from mucosal effector memory CD4+ T cells in chronic colitis mice

Colitogenic memory CD4+ T cells are important in the pathogenesis of inflammatory bowel disease (IBD). Although memory stem cells with high survival and self-renewal capacity were recently identified in both mice and humans, it is unclear whether a similar subset is present in chronic colitis mice. We sought to identify and purify a long-lived subset of colitogenic memory CD4+ T cells, which may be targets for treatment of IBD. A long-lived subset of colitogenic memory CD4+ T cells was purified using a long-term culture system. The characteristics of these cells were assessed. Interleukin (IL)-7 promoted the in vitro survival for >8 weeks of lamina propria (LP) CD4+ T cells from colitic SCID mice previously injected with CD4+CD45RBhigh T cells. These cells were in a quiescent state and divided a maximum of 5 times in 4 weeks. LP CD4+ T cells expressed higher levels of Bcl-2, integrin-α4β7, CXCR3 and CD25 after than before culture, as well as secreting high concentrations of IL-2 and low concentrations of IFN-γ and IL-17 in response to intestinal bacterial antigens. LP CD4+ T cells from colitic mice cultured with IL-7 for 8 weeks induced more severe colitis than LP CD4+ T cells cultured for 4 weeks. We developed a novel culture system to purify a long-lived, highly pathogenic memory subset from activated LP CD4+ T cells. IL-7 promoted long-term in vitro survival of this subset in a quiescent state. This subset will be a novel, effective target for the treatment of IBD.

Adaptive growth responses of Listeria monocytogenes to acid and osmotic shifts above and across the growth boundaries.

The effect of acid and osmotic shifts on the growth of Listeria monocytogenes was evaluated at 10°C. Two types of shifts were tested: (i) within the range of pH and water activity (a(w)) levels that allow growth of L. monocytogenes and (ii) after habituation at no-growth conditions back to growth-permitting conditions. A L. monocytogenes cheese isolate, with high survival capacity during cheesemaking, was inoculated (10(2) CFU/ml) in tryptic soy broth supplemented with 0.6% yeast extract at six pH levels (5.1 to 7.2; adjusted with lactic acid) and 0.5% NaCl (a(w) 0.995), or four a(w) levels (0.995 to 0.93, adjusted with 0.5 to 10.5% NaCl) at pH 7.2 and grown to early stationary phase. L. monocytogenes was then shifted (at 10(2) CFU/ml) to each of the aforementioned growth-permitting pH and a(w) levels and incubated at 10°C. Shifts from no-growth to growth-permitting conditions were carried out by transferring L. monocytogenes habituated at pH 4.9 or a(w) 0.90 (12.5% NaCl) for 1, 5, and 10 days to all pH and a(w) levels permitting growth. Reducing a(w) or pH at different levels in the range of 0.995 to 0.93 and 7.2 to 5.1, respectively, decreased the maximum specific growth rate of L. monocytogenes. The lag time of the organism increased with all osmotic downshifts, as well as by the reduction of pH to 5.1. Conversely, any type of shift within pH 5.5 to 7.2 did not markedly affect the lag times of L. monocytogenes. The longer the cells were incubated at no-growth a(w) (0.90), the faster they initiated growth subsequently, suggesting adaptation to osmotic stress. Conversely, extended habituation at pH 4.9 had the opposite effect on subsequent growth of L. monocytogenes, possibly due to cell injury. These results suggest that there is an adaptation or injury rate induced at conditions inhibiting the growth of the pathogen. Thus, quantifying adaptation phenomena under growth-limiting environments, such as in fermented dairy and meat products or products preserved in brine, is essential for reliable growth simulations of L monocytogenes during transportation and storage of foods.

Lipid dynamics during early development of Hippocampus guttulatus seahorses: Searching for clues on fatty acid requirements

The biochemical composition of eggs and the nutrient dynamics during early ontogeny can provide better understanding on the nutritional requirements of both broodstock and first-feeding fish, thus constituting a valuable tool for improvement of aquaculture procedures. This study constitutes the first record of lipid composition and fatty acid dynamics during early development of seahorses. Lipid content and fatty acid profile were determined for Hippocampus guttulatus eggs and newborn juveniles, and their patterns of consumption were analyzed during embryonic development. H. guttulatus produced small broods (426 ± 128 juveniles) but invested in the production of large eggs (2.44 ± 0.37 mm) that resulted in large fingerlings (15.53 ± 1.28 mm), which may have a high survival capacity. The total lipid content of seahorse eggs (17.6% DW) was within the typical range of marine fish eggs. Eggs were dominated by PUFA (43.9%), mainly n−3 HUFA (17.4% of DHA and 13.2% of EPA), and showed a lower MUFA content (22.5%). Extremely low AA levels (0.6%) and particularly high EPA concentrations resulted in a low DHA:EPA ratio (1.3) and high EPA:AA (22.3) and n−3:n−6 (12.2) ratios. Fatty acid consumption during embryonic development was considerably high (67.8%), reflecting the high requirements of seahorse embryos. Fatty acids were depleted at different rates, with PUFA being preferentially consumed (75.2%), while SFA were selectively retained (59.2%). PUFA constituted the major source of metabolic energy and the fatty acids 16:0, EPA and DHA were the main fatty acids to fulfill the energetic demands of seahorse embryos. Essential fatty acids (AA, EPA and DHA) were not preferentially retained, with EPA being catabolized at a particularly high rate (88.0%). These patterns of embryonic consumption resulted in newborn juveniles with an exceptionally low lipid content (5.0% DW), a predominance of SFA (41.0%) and extremely low EPA levels (5.0%). Fatty acid composition of H. guttulatus eggs and juveniles provided important clues to determine seahorse requirements, so that suitable feeding protocols could be developed. The use of broodstock and juvenile diets that reflect the lipid profile of eggs will allow the accomplishment of nutritional requirements and improvement of seahorse production.

Could side population cells be an indicator of progression to hormone nonresponsive breast cancer

There is increasing evidence that recurrent metastatic breast cancer arises in part due to the presence of long-lived, slow-cycling, and drug-resistant stem cells. Adult stem cells, known as side population (SP) cells, whose phenotype has been demonstrated to be due to the expression of ABCG2, are known to be resistant to a number of structurally unrelated compounds. In the present study we have observed that while both oestrogen-responsive and non-oestrogen-responsive breast cancer cell lines contain SP, exhibit multidrug resistance and express elevated levels of ABCG2, the non-oestrogen-responsive more highly metastatic MDA-MB-231 SP cells exhibit higher levels of mitoxantrone resistance than the other cell populations examined. These SP cells would therefore have a higher survival capacity when exposed to many currently utilised therapeutic regimes. Importantly, we have shown there is a statistically significant relationship between the presence of these SP cells in fine needle aspirates associated with ER-negative palpable breast lesions, and that these cells are more frequently associated with triple-negative breast tumours. Novel treatments directed against SP cells should be sought to offer patients better treatment strategies in these triple-negative tumours that fail to respond to conventional targeted therapy. Further analysis of this small population of potentially important cells is warranted.

Dietary effects of n-3 highly unsaturated fatty acid levels on egg and larval quality, and the fatty acid composition of the eggs of Chilean flounderParalichthys adspersusbroodstock

The effects of dietary n-3 highly unsaturated fatty acid (n-3 HUFA) on eggs and larval quality were investigated in the Chilean flounder Paralichthys adspersus. Broodstock were fed with three formulated diets with similar proximate compositions but different n-3 HUFA (2.1%, 3.1% or 4.1%) estimated levels from 5 months before and during the spawning period. The diet with an intermediate n-3 HUFA level resulted in a significantly higher (P<0.05) percentage of buoyant eggs (68.2 ± 2.9%), fertilization (92.8 ± 3.9%), normal cell cleavages (93.5 ± 1.9%), hatching rate (87.7 ± 4.1%) and normal larvae (76.3 ± 3.7%) compared with the other two diets. In contrast, high levels of n-3 HUFA produced larvae with a higher survival capacity when subjected to fasting. The diet with the lowest content of n-3 HUFA produces lower quality eggs and larvae. The n-3 HUFA level in eggs increased with an increase in the dietary level, and the n-3/n-6 ratios were 1:1, 2:1 and 3:1. The DHA/EPA and EPA/ARA ratios of 2 and 4 in eggs, respectively, were associated with improved egg and larval quality and were similar to the ratios found in eggs from wild broodstock. Attainment of optimal fatty acid contents in broodstock diets is one of the key factors for producing the high-quality spawning required for managed culture of this flounder.

간기능 개선용 복합 식물 추출물(Hepa-1000)의 tert-butyl hydroperoxide(t-BHP)로 유도한 간세포 독성에 대한 보호 효과

본 연구에서는 간기능 개선제(Hepa-1000)의 t-BHP에 의해 유도된 산화적 스트레스에 대한 간세포 보호 효과를 확인하기 위해 인간 간암 세포주인 HepG2 세포를 이용한 세포실험으로 검증하였다. 간세포에 t-BHP로 유도되는 간세포의 산화적 손상에 대한 보호 효과를 측정한 결과, Hepa-1000을 처리시 대조군에 비해 유의적인 세포 생존율 증가치를 보이므로 간기능 개선제(Hepa-1000)가 t-BHP에 의한 간세포의 괴사에 대해 강한 보호 효과가 있음을 알 수 있었다. 또한 간기능 개선 효능을 확인하기 위해 세포 배양액 내의 GOT와 LDH의 활성도를 측정 시 t-BHP에 의해 간세포 손상이 확연하게 유발되었으며, 간기능 개선제(Hepa-1000)는 GOT와 LDH의 증가를 유의적으로 뚜렷하게 억제하였다. Hepa-1000의 t-BHP에 의해 유도된 산화적 스트레스에 대한 보호 효과를 세포막 손상 시 배양액 내의 세포 지질과산화 정도를 측정하는 MDA양을 측정하였을 때, Hepa-1000을 처리시 MDA의 양이 감소함을 관찰할 수 있었다. 이러한 결과들을 종합해 볼 때 간기능 개선제인 Hepa-1000은 간세포에서 t-BHP의 대사과정시 발생되는 free radical에 의한 세포내 지질과산화 현상을 방어하여, 세포막 손상 시 배양액으로 유출되는 GOT, LDH의 양을 감소시키므로 산화적 스트레스에 의한 간세포의 손상을 보호함으로써 인체에서 해독작용을 담당하는 조직인 간의 기능을 개선시키고 보호하는 효과를 나타내리라 사료된다.

The dispersal characteristics of the invasive plant Mimulus guttatus and the ecological significance of increased occurrence of high‐flow events

Summary Increased occurrence of high‐flow events as a result of climate change may affect the dispersal success of an invasive plant species Mimulus guttatus and may result in range expansion. Predicted changes in climate point to a continuation of the recent observed trends in increased precipitation and high‐flow events in Northern Europe. The study focused on the dispersal characteristics of M. guttatus, and especially the roles of vegetative fragmentation with increasing water velocities, subsequent fragment survival, regeneration and colonization, as well as the buoyancy, survival and germination success of seeds. M. guttatus was found to fragment readily under velocities typical of high flow conditions and even small fragments had high survival, regeneration and colonization capacity. Large numbers of small (&lt; 0.02 mg) seeds are produced; however, seeds have a short buoyancy period so the timing and magnitude of high‐flow events is crucial in determining potential dispersal distances. Seeds germinate readily both in water and on sand with an average 33% germination within 9 days. The dual strategy of dispersal by vegetative fragments and seeds, together with the opportunity of dispersing the two types of propagules during different periods of the year, facilitates local dominance by M. guttatus as well as long‐distance colonization. As a result, the rate of spread of M. guttatus into inundation communities along rivers is likely to increase with more frequent high‐flow events, especially if these coincide with the growing season. Thus, predicting the response of riparian invasive species to environmental change requires not only an understanding of the role of climate in plant demography but also the impact of changes in hydrology on rates of spread.

Review article: bifidobacteria as probiotic agents – physiological effects and clinical benefits

Bifidobacteria, naturally present in the dominant colonic microbiota, represent up to 25% of the cultivable faecal bacteria in adults and 80% in infants. As probiotic agents, bifidobacteria have been studied for their efficacy in the prevention and treatment of a broad spectrum of animal and/or human gastrointestinal disorders, such as colonic transit disorders, intestinal infections, and colonic adenomas and cancer. The aim of this review is to focus on the gastrointestinal effects of bifidobacteria as probiotic agents in animal models and man. The traditional use of bifidobacteria in fermented dairy products and the GRAS ('Generally Recognised As Safe') status of certain strains attest to their safety. Some strains, especially Bifidobacterium animalis strain DN-173 010 which has long been used in fermented dairy products, show high gastrointestinal survival capacity and exhibit probiotic properties in the colon. Bifidobacteria are able to prevent or alleviate infectious diarrhoea through their effects on the immune system and resistance to colonization by pathogens. There is some experimental evidence that certain bifidobacteria may actually protect the host from carcinogenic activity of intestinal flora. Bifidobacteria may exert protective intestinal actions through various mechanisms, and represent promising advances in the fields of prophylaxis and therapy.